What carpet cleaner machines are safe for carpets over hardwood floors?

I had a hoover which had written on the box that it was meant for hardware floors. It had a squeegie like attachment for the nozzel that sucked up the water. That being said, it's risky. I would use a dedicated floor steam cleaner like a Haan which is cheaper then a steam cleaner. Letting any water seep into wood will eventually cause it to crack and split on the ends.